Hepatitis C virus (HCV) is the major etiological agent of 90% of all cases of non-A, non-B hepatitis (Choo et al., 1989, Kuo et al., 1989). The incidence of HCV infection is becoming an increasingly severe public health concern with 2-15% individuals infected worldwide. While primary infection with HCV is often asymptomatic, most HCV infections progress to a chronic state that can persist for decades. Of those with chronic HCV infections, it is believed that about 20-50% will eventually develop chronic liver disease (e.g. cirrhosis) and 20-30% of these cases will lead to liver failure or liver cancer. As the current HCV-infected population ages, the morbidity and mortality associated with HCV are expected to triple.
An approved treatment for HCV infection uses interferon (IFN) which indirectly effects HCV infection by stimulating the host antiviral response. IFN treatment is suboptimal, however, as a sustained antiviral response is produced in less than 30% of treated patients. Further, IFN treatment induces an array of side effects of varying severity in upwards of 90% of patients (eg: acute pancreatitis, depression, retinopathy, thyroiditis). Therapy with a combination of IFN and ribavirin has provided a slightly higher sustained response rate, but not alleviated the IFN-induced side effects.
The use of protease inhibitors, particularly those selectively targeting HCV serine protease, has great potential to be useful in treating HCV infections in patients by inhibiting HCV replication.
Amongst the compounds that have demonstrated efficacy in inhibiting HCV replication, as selective HCV serine protease inhibitors, are the macrocyclic peptide compounds disclosed in International Application PCT/CA00/00353 (Publication No. WO 00/59929). The present invention describes selective inhibitors of the HCV NS3/NS4A serine protease complex of improved chemical design relative to the previously described invention, that have the potential to demonstrate suitable whole cell permeability for the treatment of HCV-infected patients.